AJP - Endocrinology and Metabolism, Vol 268, Issue 4 E752-E757, Copyright © 1995 by American Physiological Society
High-fat feeding alters the response of rat PDH complex to acute changes in glucose and insulin
J. M. Bryson, G. J. Cooney, V. R. Wensley, J. L. Phuyal, M. Hew, G. S. Denyer and I. D. Caterson
Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
The activity of the pyruvate dehydrogenase complex (PDHC) was studied in
tissues of controls and insulin-resistant fat-fed rats (FFR) both in the
fed state and in overnight fasted animals after the induction of short-term
changes in plasma insulin by an intravenous glucose load. Significant
responses by the PDHC to the glucose challenge were seen in heart and white
adipose tissue (WAT) in controls with smaller changes in brown adipose
tissue (BAT) and quadriceps muscle (QM) and no change in liver. Reduced
PDHC responses and lower fed values were seen in heart and BAT of FFR. The
response in WAT of FFR was prolonged with no change in the PDHC response in
QM. Plasma nonesterified fatty acids (NEFA) were decreased in response to
the glucose load with no differences between controls and FFR. Tissue
triglyceride levels were higher in liver and QM but not heart of FFR. These
results show differential tissue PDHC responses to short-term changes in
plasma insulin. The decreased PDHC activity in some tissues of the fat-fed
animals despite the lack of change in plasma NEFA, together with the
triglyceride accumulation seen in some tissues but not others, suggests
that local intracellular fatty acid metabolism is important in the
regulation of intracellular glucose oxidation.
